1. Field of the Invention
The present invention relates to a flexible, jointed suction arm for gaseous fluids.
This arm comprises a first end and a second end; the first end is fastened to a support; its second end is free, provided with a suction funnel and is movable in all directions according to requirements while remaining, in the absence of any external control action, in the position in which it was previously brought. This suction arm is adapted to suck in dangerous or polluting smokes or vapors, dust, and/or solid particles in suspension in the atmosphere, in the vicinity of a working station (painting cabs, welding rooms, etc.).
2. The Prior Art
Suction arms of this type are already known. In a first form of embodiment the conduit is completely flexible and supported by a deformable suspension device, so that the assembly is rather complex, expensive, cumbersome and awkward. If the suspension device is disposed within the conduit, the suction output is reduced and the suspension device itself is exposed to the corrosive action of the gaseous fluid flowing in the conduit. In another known structure the suction arm comprises a sequence of rigid tubular sections coupled by means of joints and external holding means (cf. U.S. Pat. No. 3,298,544), thus constituting a complicated assembly scarcely adapted for the use contemplated and ill suited for temporarily interlocking the tube sections.
In a third form of embodiment the suction arm comprises a series of successive rigid tubes and flexible sleeves. The rigid tubes are hingedly interconnected by coupling means comprising a brake. Linear compensating springs such as coil springs are attached to external points of the arms in order to preserve the arm balance in its various positions. This construction is attended however by various inconveniences; thus, the linear coil spring increases the overall dimensions of the arm, which may prove detrimental in actual operation. Besides, the spring is exposed to accidental external actions likely to jeopardize the operator or operators and to damage the arm proper. Furthermore, the spring does not operate under optimal conditions since it opposes a linear return force to the torque reaction resulting from the weight of the overhanging arm. This return force is not subordinate only to the relative position of the successive sleeves. The return force of this spring is limited and consequently either the suction power of the arm is limited or the operator is compelled to constantly move the arm in order to bring same in close vicinity of the working station. In this case the movements imparted to the arm are not only numerous but also inaccurate and rude. Moreover, in this known structure, it is not possible to provide a spring for each flexible sleeve, if this measure were deemed necessary. Finally, the arm cannot be locked in all the desired positions and the end suction nozzle cannot be moved in all directions about a point. Therefore, an arm of this specific type is awkward, has a reduced power, is dangerous in operation and requires many movements.